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Influenza
is a group of RNA virus which causes respiratory disease of the family Orthomyxoviridae, genus "Influenza virus A","Influenza virus B","Influenza virus C" and respective species A, B, and C it is likely that all the epidemics of influenza derived from humans living in close proximity to poultry or pigs, and poultry is a natural reservoir for the disease. Of the 3 main subtypes (A,B,C) A is responsible for the major pandemics of human flu infections including Spanish flu of 1918 and Swine Flu of 2009. The disease is transmitted by airborne particles and infects the epithelial cells of the upper respiratory tract. @todo some images of infection and cells http://www.technion.ac.il/~mdcourse/274203/lect13.html http://www.comprehensivephysiology.com/WileyCDA/CompPhysArticle/refId-cp030211.html Structure the capsid contains a single strand (-ssRNA) of RNA and the viral enzyme RNA polymerase around the capsid there is a membranous envelope which contains neuraminidase (NA) and haemagglutinin (HA) patrick 2009 haemagglutinin is named because it can bind to red blood cells and causes haemagglutinination The glycoproteins HA and NA are spike like, protruding 10nm from the surface of the virion Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending extracellularly, the extracellular segments are often glycosylated. Glycoproteins are often important integral membrane proteins, where they play a role in cell–cell interactions. Subtypes IN virus classification, the family Orthomyxoviridae contain a number of genera, including a genus for each influenza A, B and C, however each genus contains only a single species, that corresponding to the genus name. INfluenza typa C undergoes little antigenic variation, and B only drifting at a slow pace. However subtype A mutates yearly and is the major source of health problems. The N and the H in N1H1 refer to the antigens of N of NA and the H of HA respectively in the near shift occurs, the emergence because of Asian flu (H2N2) lack immunity to H2N2 will effect younger people, because they have no immunity to H2N2 for 40 years type C can be divided into serotypes based on the antibody reponses to the antigen changes to the N and H proteins. Viral Proteins 3 transmembrane proteins NA HA Lifecycle Drugs Amantadine the first antiviral approved for Influenza was Amantadine hydrochloride Amantadine is not effective against influenza B or C Is administired orally, but is associated with neurological disorders in a subset of patients Rimatadine derivative of Amantadine, deliverd orally Ribavirin 1972 GG167 poor absorption via GI congener of neuraminic acid PM-523 inhibits fusion of virus for influenza A phagosome A phagosome is a vesicle formed around a particle absorbed by phagocytosis. The vacuole is formed by the fusion of the cell membrane around the particle. A phagosome is a cellular compartment in which pathogenic microorganisms can be killed and digested. Phagosomes fuse with lysosomes in their maturation process, forming phagolysosomes. Some bacterial pathogens that enter cells inside phagosomes either reproduce inside of the formed phagolysosome or escape into the cytoplasm before the phagosome fuses with the lysosome. Many mycobacteria, including Mycobacterium tuberculosis 3 4 and Mycobacteria avium paratuberculosis, manipulate the host macrophage to prevent nitrous acid-containing lysosomes from fusing with phagosomes and creating mature phagolysosomes. Such incomplete maturation of the phagosome maintains an environment favorable to the pathogens inside it. http://en.wikipedia.org/wiki/Phagosome During the adsorption phase of the viral lifecycle, the low pH of the endosome causes a conformal change in the HA2 protein which opens up ... This process of penetrating target cells is unique to influenza viruses BMY-27709